This invention relates to the field of emergency medical radios, and more particularly, to an improved and faster means of checking the ECG electrode impedances before ECG telemetry begins.
Emergency medical radios are known in the art to provide two-way communication between a paramedic team on the scene of an emergency and a hospital, plus the capability of relaying to the hospital vital signs such as electrocardiogram signals (ECG) for expert analysis. After analysis, advice will be transmitted back as to the proper treatment to be administered. Such systems may utilize direct broadcast, relayed broadcast or telephone line transmissions, depending on the circumstances. In the typical operation, a paramedic will make contact with the hospital by voice, send a calibrating signal, test the electrode resistances, then begin the actual telemetry. It is important to test the electrode resistance at the scene, since the paramedic does not see a print out of the ECG signal and would have to be alerted by the hospital if a bad connection or open line existed. Since time, even a few seconds, may be a matter of life or death for an accident or heart attack victim, any time wasted or a faulty transmission could have tragic consequences.
Also in the prior art, electrodes have been checked with direct current, and because of the chemistry involved, a coating which was a semiconductor, could be produced on the electrodes. Thus the level of contact resistance could become higher and higher, with resulting loss of accurate signals.